High-pressure process for making puffed food product and product

ABSTRACT

The process for producing a puffed food product having a highprotein level from a combination of legumes and cereal grains by subjecting the raw food product to high pressures and temperatures to produce a sheet of product having relatively high-protein-content and crunchy texture.

United States Patent Mullen et al.

[4 1 Jan. 25, 1972 [54] HIGH-PRESSURE PROCESS FOR MAKING PUF FED FOODPRODUCT AND PRODUCT [72] Inventors: Joseph D. Mullen, Golden Valley;Alide Ogrins, St. Paul; Ali R. Touba, Crystal, all

of Minn.

[73] Assignee: General Mills, Inc.

[22] Filed: Mar. 26, 1969 [21] Appl. No.: 810,776

[52] U.S. Cl ..99/83, 99/82,,99/98 [5 1] Int. Cl ..A23l 1/18, A231 1/20[58] Field of Search .99/82, 83, 90 HP, DIG. 4, 80,

Primary Examiner Raymond N. Jones Assistant ExaminerWilliam AndrewSimons Attorney-Anthony A. Juettner, William C. Babcock and Harold D.Jastram [57] ABSTRACT The process for producing a puffed food producthaving a high-protein level from a combination of legumes and cerealgrains by subjecting the raw food product to high pressures andtemperatures to produce a sheet of product having relativelyhigh-protein-content and crunchy texture.

5 Claims, No Drawings HIGH-PRESSURE PROCESS FOR MAKING PUFFED FOODPRODUCT AND PRODUCT The invention relates to a product and process forproduction of a high-protein food product incorporating the bestcharacteristics of cereal grains and the best characteristics oflegumes.

More specifically, the invention relates to combining cereal grains withlegumes in order to produce a food product having the high-proteincharacteristic of legumes, such as soybean and the like, together withthe many characteristics of cereal grains, including process ofadaptability, appearance, desirable eating qualities, food consumptionqualities and amino acidbalance.

Cereal grains have long been a mainstay of the food industry for theproduction of high-quality food products of all types. These includefinished products, such as ready-to-eat breakfast cereals, various typesof pastries including bread, certain candy bars and the like. The foodindustry has utilized cereal grains for a number of reasons. First ofall, cereal grains provide a number of the vitamin, mineral and othernutritive qualities necessary in food products. Further, cereal grainshave been relatively easy to process and convert to attractive, easilychewable and readily consumable finished food product, which may bereadily preserved while the product is transferred through thedistribution channel of trade to the consumer.

While cereal grains are excellent raw food material, they do lackcertain advantages of other raw food materials. For instance, cerealgrains are not as high in protein as some other natural foods, such asmeat. Accordingly, they do not provide the level of protein that manypeople desire or need in a food product. Furthermore, the cereal grainsare not complete foods in that they are low in the amino acid lysine,which is essential for proper nutrition.

Legumes, such as soybeans, peas, and the like, are a food product thatare known to be very high in protein. Soybeans, for example, have aprocessed protein level which might be equal to or higher than many meatproducts. Further, these legumes appear to have high-protein levelnecessary for good nutrition and are relatively high in the amino acidlysine. These legumes, on the other hand, do not possess. all of thedesirable characteristics necessary for good food-processing procedures.Legumes have low levels of the amino acid methionine which is necessaryfor a well-balanced diet. Also, it has been found that a legume issomewhat difiicult to handle in order to produce a finished productwhich is tasty and easy to chew.

Accordingly, it has been found that it is possible to combine a cerealgrain with a legume and thereby utilize the best characteristics of eachof these raw food materials to produce a very palatable finished foodproduct which is high in protein and which has excellent nutritivecharacteristics in addition to excellent taste, texture, palatabilitycharacteristics and good amino acid balance.

Typically food products, such as noted above, are processed by soaking,grinding, cooking, mixing and similar steps after which the products arecooked, toasted, pufl'ed, sheeted or otherwise baked to develop flavor.These various steps are usually taken in order to arrive at one or moredesired end products such as puffed breakfast cereals, cookies, biscuitsand the like. For instance, in the cereal industry, frequently wholekernels of grain are individually puffed to permit them to be used as aready-to-eat breakfast cereal. Typically before the individual grainscan be puffed, they must be soaked and otherwise prepared for thepuffing operation, after which they are toasted and flavored. Likewise,in the baking industry, these same cereal grains or legumes are firstground to a fine consistency. This grinding obviously is a step toimprove the chewabilityof the product. After the grinding, the productis then frequently, mixed with one or more other ingredients or mixedwith water in order to produce an end product by baking to developflavor and texture. It can be seen that all of these methods involve anumber of individual steps which must be carried out in a predeterminedorder thus requiring the expenditure of a great deal of time and effortto produce a chewable, consumable product. The present process may beutilized to produce a new product which eliminates many of the usualtime consuming, expensivesteps practiced in the food industry. Theprocess involves placing granulations of legumes and cereals together toform a mixture having the desired nutritional characteristics. Thiscombined mixture is then agglomerated to form particles combining theindividual particles of the legume and cereal grain. Agglomeration isdefined in this application to mean a production of a wet mass ofparticles stuck together in the form of granules with the aid ofmoisture with sufficient cohesion to permit the granules to bedried.'There are a number of ways known inthe art for accomplishingthis. For example, one such method for doing this is subjection of thewetted ground particles to mechanical agitation. Another processinvolves fluid bed techniques. Any of these methods might be utilized toform the wet granules. After the granules are formed, they are dried toa suitable moisture level after which they are subjected to mechanicalpressures and high temperatures. The pressure is suddenly release fromthe product which causes the finished product to expand or become puffedand thereby cause the individual particles to become cemented togetherto form a sheet or wafer of food product.

The product formed according to the above-noted process takes on theappearance of a mosaic sheet having a pattern which is predetermined bythe granule and particle size and shape used in the process. The foodproduct also takes on a textured appearance due to the differing puffingcharacteristics of the legume and cereal. The cereal tends to puff muchmore than the legume with the result-that there are high and low surfaceareas. The cereal forms the high surface and the legume the low surfacethus resulting in a product having a very pleasing appearance andtexture.

The naturalingredients of the raw material provides the cementingingredient for producing a wafer or sheet of puffed food product whichis high in protein and which takes on a toasted flavor as a result ofthe application of high temperatures during the puffing and cementingoperations. The protein and carbohydrate fractions produced by the heatand pressure are believed to bethe bonding agents. The finished productalso is crunchy, almost crumbless, and may be flavored by the use ofoils, such as vegetable oil. 0

Accordingly, it is noted that the product produced by this inventioneliminates many of the processing steps heretofore practiced in the foodindustry for producing a finished puffed food product and additionallythe invention provides a new high-protein food product in palatable formcombining the best attributes of a variety of food products.

In accordance with the present invention, a legume, such as peas,lentils, soybeans, chickpeas and the like, may be cooked and ground toprovide a flour. The particle size of the flour may vary; however, apreferred. particle size is about 0.05 inches. Next, a cereal grain,such as wheat, rice, barley, oats, corn, popcorn, millet, sorghum orsimilar grains, is selected. For the purpose of describing theinvention, rice will be utilized as the cereal grain. The rice productis ground to form a flour which has a particle size of about 0.009inches to about 0.066 inches. The legume flour and the cereal flour arethen combined to form a flour mixture wherein at least 30 percent iadded to the mixture in order to form granules of the mixed legume andcereal grain which are strong enough to withstand further handling andheating for drying purposes. These granules normally form in randomsizes which is satisfactory for producing an attractive finishedproduct. After the granules have been formed, they are dried to reducethe overall moisture level. The granules are dried to reduce themoisture content by weight to about 8 to 16 percent. It has been foundthat a granule having 16 percent by weight of moisture, for example,will produce a puffed product having a very low density whereas aproduct having a moisture level of 8 percent by weight will not puffnearly so much and will be rather dense. Accordingly, it has been foundthat a very satisfactory product combining most optimum characteristicsis prepared from granules which have been dried in the range of l l toabout 13 percent by weight. The drying can take place in a forced draftoven and temperatures in the range of 85 C. to 90 C. have been foundsufficient to provide a satisfactorily dried product.

The dried granular material is then placed between the plates of amechanically operated press which squeezes the product between plates toa pressure of not less than 100 pounds per square inch. Application ofpressures up to 1,000 pounds per square inch have been found to providea very satisfactory product. The choice of pressure to be applied to aparticular product will depend to some extent upon the desiredcharacteristics of the end product. For instance, it has been'found thatapplication of the higher pressures to the food product will result inless time required to heat the product and thereby achieve the desiredflavor and physical characteristics for the finished product. It hasbeen found that a very short cooking time is necessary to produce afinished product by the application of pressure in the range of 100pounds per square inch to 1,000 pounds per square inch since the timerequired to pufi' and cook the product is about 1 second to about 30seconds.

Heat is applied to the product while it is being subjected to themechanical pressure. When temperature in the range of 300 F. to about700 F. are combined with pressures in the range of 100 pounds per squareinch to about 1,000 pounds per square inch, a puffed and cooked producthaving toasted flavor is achieved. The time necessary to achieve thisresult is very short, in the neighborhood of about 1 second to about 30seconds. The puffing occurs as the mechanical pressure on the heated rawmaterial is suddenly released and the elevated temperatures of the foodproduct cause expansion of the moisture in the food product and therebypuffs the individual particles of raw material.

The release of the mechanical pressure on the raw material wasdiscovered to achieve another desired result, namely, a cementing of theindividual raw material particles. and granules together. it was foundthat as the pressure was suddenly release from the raw material, theindividual particles puffed and expanded to a considerable degree. Theexpanding particles and granules contacted each other and they becamecemented together very firmly. No ingredient was added to the rawmaterial to accomplish this cementing action but it was observed that avery strong bond was created. Presumably, the naturally occurringingredients in the legumes and grains, when elevated to the above-notedtemperature, act as to a cementing agent, and as the individualparticles were expanding due to the release of temperature, thesenaturally occurring ingredients formed a bond to produce a puffed waferor sheet having an attractive mosaic pattern. lf was found that the useof a lower pressure produced a product with somewhat less cohesivecharacteristics after puffing. The products puffed to a satisfactorydegree and formed a satisfactory wafer or sheet; however, it was foundthat as the product was broken, that the cemented bond seemed to havesomewhat less strength than if the higher pressures were used to formthe product. In some situations, it may be desirable to have a productwith a weaker bond, thus permitting the product to more readilydisintegrate in the mouth of the consumer as the product is eaten. Onthe other hand, if it is anticipated that the product will be subjectedto severe handling conditions during marketing of the product, thehigher pressures might be utilized in order to achieve a stronger bondand thereby prevent damage to the product in transit.

One of the outstanding characteristics of this product was discovered tobe the relatively crumbless nature of the product as it is broken oreaten bythe consumer. When a bite is taken from a wafer-size product,there is no tendency for the product to crumb in the sense that a cookieor similar food product will crumb. The cementing which occurs betweenthe individual particles of the raw material is credited with providingthis anticrumb characteristic. I

After the product has been puffed and cemented, it is dipped in oil toflavor the product. The oil which may be used to flavor the product maybe either animal or vegetable in origin; however, preferably a vegetableoil is used. Vegetable oils, such as coconut oil, corn oil, cottonseedoil, safflower oil and the like, have been found to be successfully usedto achieve a very tasty product. An example of a method for coating theproduct with oil would be to dip the finished sheets into oil which isheated to 200 C. The oil-coated product is then flavored with salt,seasonings and the like if a variety of flavors might be desired.

A more complete understanding of the product and process maybe achievedby reference to the following examples of specific products which wereproduced according to the invention. Y

EXAMPLE I Raw whole chickpeas were cooked at 460 F. while beingsubjected to high pressures. The peas were cooked for about I to 2seconds and were then ground to a particle size of about 0.050 inches.Rice was ground to a fineness whereby it would pass through a US.standard sieve No. 8. The ground chickpeas and rice were then mixedaccording to the following formula:

100 grams of chickpeas 50 grams of ground rice.

This mixture was then agglomerated by adding about l 13 ml. of tap waterduring the agglomeration. This formed granules of wet mixture which wasthen dried in a forced draft oven at temperatures of to about C. untilthe moisture content of the individual granules was reduced to llpercent by weight. The dried, granules were then placed between theplates of a hydraulically operated press where they were subjected to apressure of 1,000 pounds per square inch and heated to a temperature of460 F. for about one second. The pressure was rapidly released so thatthe resulting product became puffed and the individual particles andgranules became cemented together to form a sheet of food product havinga mosaiclike appearance. The chickpeas provided a light brown colorationto the finished product and the rice particles provided a lighter colorwhich was randomly distributed throughout the finished product. Thepuffed and finished product was then dipped in coconut oil, heated to,200 C. and lightly salted to provide a high protein, puffed, saltedsnack having a somewhat toasted flavor.

EXAMPLE n Example ll was prepared in exactly the same fashion as setforth in example I above except that the legume used was green peas.

Example lll Example lll was prepared substantiaily the same as example Iwith certain variations. In this example, the legume used was soybeanflour. Rice was used having a granular size which passed through a US.standard sieve No. 12. The soybean and rice flour was mixed in equalportions and was then agglomerated by using 250 ml. of water for a totalof 400 grams of the combined soy and rice flours. The water used foragglomeration contained the following ingredients.

0.3 grams monosodium glutamate 12.0 grams salt 4.0 grams nonfat milksolids 4.0 grams corn sugar 4.0 grams melted coconut oil A pastelikeproduct was produced which was then passed through a US. standard sieveNo.6 in order to provide granules of material. These granules were thendried in a forced draft oven at a temperature of about 77 C. to about 85C. to lower the moisture content of the particles to about 14 percent byweight. The dried mixture was the screened through a US. standard sieveNo. 16 to remove the fines. The coarse portion was puffed in the samefashion as described in example I except that 800 pounds per square inchof force was applied to the product for less than a second as theproduct was heated to temperatures of 460 F. The resulting productresembled in apppearance and texture the product of example I. Theproduct as in example I was then coated with coconut oil, heated to atemperature of 200 C. and was then salted for flavor.

EXAMPLE IV Example 1V is exactly the same as example Ill except that soygrits were substituted for soy flour.

The protein level of the products prepared according to the aboveexamples was calculated according to the data from USDA AgriculturalHandbook No. VIII and the following protein levels were found in thevarious examples:

Approximate Percentage Protein After dip- Example puffing ping in oil lll7 12 Ill 27 18 It will be observed from these protein levels that thefinished product is relatively high in protein. In addition, it is notedthat the amino acid balance provided by both legumes and cereal productsis excellent since adequate levels of lysine and methionine are presentin the finished product.

It is to be noted that there are a number of variations which may bemade to the above-described invention without departing from the spiritand the scope thereof. For example, various ratios of legume to cerealmight be used. A very satisfactory ratio of chickpeas to rice was foundto be a mixture of 2 to l, and an equally satisfactory ratio of soyflour to rice mixture was found to be a l to l mixture. The optimummoisture level for the agglomerated produce appeared to be in the llpercent to 13 percent range; however, moisture levels in the 8 percentto 16 percent range, measured by weight, were also found to be verysatisfactory and produced excellent quality products.

We claim:

1. A process for forming a wafer of high-protein puffed food productwhich comprises the steps of intermixing ground cereal grain withroasted and ground legume to form a mixture composed of at least 30percent legume by weight, agglomerating the mixture with sufficientwater to produce individual sticky granules containing the ground cerealgrains and ground legume, drying the granules to a moisture level of 8to 16 percent by weight, squeezing the'granules between opposingmechanical surfaces to subject the granules to a pressure of not lessthan p.s.i., heating the granules to a temperature of from 300 F. toabout 700 F. for about 1 to about 30 seconds while the granules arebeing squeezed, rapidly releasing the pressure on the granules to causethe particles to expand and become cemented together to form a wafer ofhigh protein puffed food product and then coating the wafer with oil toflavor the wafer.

2. A process in accordance with claim 1 in which the aggolmeratedgranules are dried to a moisture level of from 1 l to about 13 percentby weight, in which the granules are squeezed at pressures of 100 p.s.i.to about 1,000 p.s.i. and in which the oil is a vegetable oil.

3. A process in accordance with claim 1 in which the ground cereal grainhas a particle size of 0.009 inches to about 0.066 inches and the groundlegume has a particle size of about 0.05 inches. 1

4. A process in accordance with claim I in which the legume is soy flourand in which the cereal grain is rice.

5. A product produced by the process of claim I.

2. A process in accordance with claim 1 in which the agglomeratedgranules are dried to a moisture level of from 11 to about 13 percent byweight, in which the granules are squeezed at pressures of 100 p.s.i. toabout 1,000 p.s.i. and in which the oil is a vegetable oil.
 3. A processin accordance with claim 1 in which the ground cereal grain has aparticle size of 0.009 inches to about 0.066 inches and the groundlegume has a particle size of about 0.05 inches.
 4. A process inaccordance with claim 1 in which the legume is soy flour and in whichthe cereal grain is rice.
 5. A product produced by the process of claim1.